xref: /openbmc/linux/drivers/watchdog/txx9wdt.c (revision d2912cb1)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
4  *
5  * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
6  */
7 
8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 
10 #include <linux/module.h>
11 #include <linux/moduleparam.h>
12 #include <linux/types.h>
13 #include <linux/watchdog.h>
14 #include <linux/init.h>
15 #include <linux/platform_device.h>
16 #include <linux/clk.h>
17 #include <linux/err.h>
18 #include <linux/io.h>
19 #include <asm/txx9tmr.h>
20 
21 #define WD_TIMER_CCD	7		/* 1/256 */
22 #define WD_TIMER_CLK	(clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
23 #define WD_MAX_TIMEOUT	((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
24 #define TIMER_MARGIN	60		/* Default is 60 seconds */
25 
26 static unsigned int timeout = TIMER_MARGIN;	/* in seconds */
27 module_param(timeout, uint, 0);
28 MODULE_PARM_DESC(timeout,
29 	"Watchdog timeout in seconds. "
30 	"(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
31 	"default=" __MODULE_STRING(TIMER_MARGIN) ")");
32 
33 static bool nowayout = WATCHDOG_NOWAYOUT;
34 module_param(nowayout, bool, 0);
35 MODULE_PARM_DESC(nowayout,
36 	"Watchdog cannot be stopped once started "
37 	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
38 
39 static struct txx9_tmr_reg __iomem *txx9wdt_reg;
40 static struct clk *txx9_imclk;
41 static DEFINE_SPINLOCK(txx9_lock);
42 
txx9wdt_ping(struct watchdog_device * wdt_dev)43 static int txx9wdt_ping(struct watchdog_device *wdt_dev)
44 {
45 	spin_lock(&txx9_lock);
46 	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
47 	spin_unlock(&txx9_lock);
48 	return 0;
49 }
50 
txx9wdt_start(struct watchdog_device * wdt_dev)51 static int txx9wdt_start(struct watchdog_device *wdt_dev)
52 {
53 	spin_lock(&txx9_lock);
54 	__raw_writel(WD_TIMER_CLK * wdt_dev->timeout, &txx9wdt_reg->cpra);
55 	__raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
56 	__raw_writel(0, &txx9wdt_reg->tisr);	/* clear pending interrupt */
57 	__raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
58 		     &txx9wdt_reg->tcr);
59 	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);
60 	spin_unlock(&txx9_lock);
61 	return 0;
62 }
63 
txx9wdt_stop(struct watchdog_device * wdt_dev)64 static int txx9wdt_stop(struct watchdog_device *wdt_dev)
65 {
66 	spin_lock(&txx9_lock);
67 	__raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
68 	__raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
69 		     &txx9wdt_reg->tcr);
70 	spin_unlock(&txx9_lock);
71 	return 0;
72 }
73 
txx9wdt_set_timeout(struct watchdog_device * wdt_dev,unsigned int new_timeout)74 static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
75 			       unsigned int new_timeout)
76 {
77 	wdt_dev->timeout = new_timeout;
78 	txx9wdt_stop(wdt_dev);
79 	txx9wdt_start(wdt_dev);
80 	return 0;
81 }
82 
83 static const struct watchdog_info txx9wdt_info = {
84 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
85 	.identity = "Hardware Watchdog for TXx9",
86 };
87 
88 static const struct watchdog_ops txx9wdt_ops = {
89 	.owner = THIS_MODULE,
90 	.start = txx9wdt_start,
91 	.stop = txx9wdt_stop,
92 	.ping = txx9wdt_ping,
93 	.set_timeout = txx9wdt_set_timeout,
94 };
95 
96 static struct watchdog_device txx9wdt = {
97 	.info = &txx9wdt_info,
98 	.ops = &txx9wdt_ops,
99 };
100 
txx9wdt_probe(struct platform_device * dev)101 static int __init txx9wdt_probe(struct platform_device *dev)
102 {
103 	int ret;
104 
105 	txx9_imclk = clk_get(NULL, "imbus_clk");
106 	if (IS_ERR(txx9_imclk)) {
107 		ret = PTR_ERR(txx9_imclk);
108 		txx9_imclk = NULL;
109 		goto exit;
110 	}
111 	ret = clk_prepare_enable(txx9_imclk);
112 	if (ret) {
113 		clk_put(txx9_imclk);
114 		txx9_imclk = NULL;
115 		goto exit;
116 	}
117 
118 	txx9wdt_reg = devm_platform_ioremap_resource(dev, 0);
119 	if (IS_ERR(txx9wdt_reg)) {
120 		ret = PTR_ERR(txx9wdt_reg);
121 		goto exit;
122 	}
123 
124 	if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
125 		timeout = TIMER_MARGIN;
126 	txx9wdt.timeout = timeout;
127 	txx9wdt.min_timeout = 1;
128 	txx9wdt.max_timeout = WD_MAX_TIMEOUT;
129 	txx9wdt.parent = &dev->dev;
130 	watchdog_set_nowayout(&txx9wdt, nowayout);
131 
132 	ret = watchdog_register_device(&txx9wdt);
133 	if (ret)
134 		goto exit;
135 
136 	pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)\n",
137 		timeout, WD_MAX_TIMEOUT, nowayout);
138 
139 	return 0;
140 exit:
141 	if (txx9_imclk) {
142 		clk_disable_unprepare(txx9_imclk);
143 		clk_put(txx9_imclk);
144 	}
145 	return ret;
146 }
147 
txx9wdt_remove(struct platform_device * dev)148 static int __exit txx9wdt_remove(struct platform_device *dev)
149 {
150 	watchdog_unregister_device(&txx9wdt);
151 	clk_disable_unprepare(txx9_imclk);
152 	clk_put(txx9_imclk);
153 	return 0;
154 }
155 
txx9wdt_shutdown(struct platform_device * dev)156 static void txx9wdt_shutdown(struct platform_device *dev)
157 {
158 	txx9wdt_stop(&txx9wdt);
159 }
160 
161 static struct platform_driver txx9wdt_driver = {
162 	.remove = __exit_p(txx9wdt_remove),
163 	.shutdown = txx9wdt_shutdown,
164 	.driver = {
165 		.name = "txx9wdt",
166 	},
167 };
168 
169 module_platform_driver_probe(txx9wdt_driver, txx9wdt_probe);
170 
171 MODULE_DESCRIPTION("TXx9 Watchdog Driver");
172 MODULE_LICENSE("GPL");
173 MODULE_ALIAS("platform:txx9wdt");
174